Add max size_type overflow check in cudf::interleave_columns

[davidwendt]

Description

Adds a check to cudf::interleave_columns() to ensure the input.num_rows() * input.num_columns() does not exceed the column size limit max(size_type).

Closes #23832

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

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• cpp/src/reshape/interleave_columns.cu

🚧 Files skipped from review as they are similar to previous changes (1)

• cpp/src/reshape/interleave_columns.cu

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📝 Walkthrough

Summary by CodeRabbit

• Bug Fixes
  • Improved the error message shown when interleaving columns exceeds the supported output size.
  • Existing validation behavior remains unchanged.

Walkthrough

Changes

Interleaved output validation

Layer / File(s)	Summary
Output size overflow diagnostic cpp/src/reshape/interleave_columns.cu	The overflow diagnostic now states that the output exceeds the column size limit. The condition and std::overflow_error exception remain unchanged.

Estimated code review effort: 1 (Trivial) | ~5 minutes

Merge Risk: 🟡 Moderate · up to 09c4c

The PR adds an overflow guard for one interleave path, but the independently callable lists implementation may remain unprotected, allowing oversized list-table inputs to bypass the check. Merge should wait for that path to be covered or for explicit owner acceptance.

Suggested reviewers: shrshi, pmattione-nvidia

🚥 Pre-merge checks | ✅ 3 | ❌ 2

❌ Failed checks (2 warnings)

Check name	Status	Explanation	Resolution
Title check	⚠️ Warning	The title claims that the pull request adds an overflow check, but the changeset summary reports only an error-message update with unchanged validation behavior.	Update the title to describe the actual error-message change, or include the claimed overflow-check implementation in the changeset.
Linked Issues check	⚠️ Warning	The linked issue requires an overflow guard before type dispatch and an equivalent guard in the independently callable lists implementation. The changeset summary shows only an error-message update an…	Add and test the size_type overflow guard in detail::interleave_columns and lists::detail::interleave_columns before dispatch.

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description check	✅ Passed	The description is related to the overflow handling in cudf::interleave_columns and identifies the linked issue.
Out of Scope Changes check	✅ Passed	The reported error-message update is related to the linked overflow-handling objective. No unrelated changes are shown.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 1 functions across 1 files.

Full details: Linked Issues check

Explanation

The linked issue requires an overflow guard before type dispatch and an equivalent guard in the independently callable lists implementation. The changeset summary shows only an error-message update and no validation change.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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Actionable comments posted: 1

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Inline comments:
In `@cpp/src/reshape/interleave_columns.cu`:
- Around line 241-244: Add the same int64_t-based row-by-column overflow
validation to cudf::lists::detail::interleave_columns before
generate_list_offsets_and_validities computes the product, or reuse a shared
validator. Ensure direct lists entry points reject products exceeding
std::numeric_limits<size_type>::max() before any size_type multiplication or
output allocation.

🪄 Autofix

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ℹ️ Review info

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📥 Commits

Reviewing files that changed from the base of the PR and between c3564ac and 247db81.

📒 Files selected for processing (1)

• cpp/src/reshape/interleave_columns.cu

Included review availability: Your plan provides up to 12 included reviews per hour; 11 remain after this review.

[davidwendt]

/merge